What is a major environmental concern associated with agrochemical use?

Pesticide resistance in pests is a significant environmental concern associated with the use of agrochemicals. When chemicals such as pesticides are applied repeatedly and overextended periods, certain pest populations may develop resistance to these substances. This process occurs through natural selection, where individuals that have mutations or genetic variations allowing them to survive exposure to the pesticide reproduce, leading to the next generation also possessing these resistance traits.

This resistance can result in a variety of negative consequences for agricultural practices. Farmers may face increased difficulty in controlling pest populations, leading to higher pesticide applications, which can perpetuate the cycle of resistance. As pests become resistant, they may require even stronger chemicals or alternative pest management strategies, which can have further detrimental effects on the environment, including increased chemical runoff, harm to non-target species, and disruptions to ecosystems.

In contrast, the other options do not reflect major environmental concerns related to agrochemical use. The improvement of soil microbiota and the better quality of water sources typically highlight beneficial outcomes rather than concerns. Increased rainfall is a natural weather pattern and does not have a direct causative relationship with agrochemical use.